Tripping mechanism



Oct. 26, 1954 E. A. E RlcsoN TRIPPING MECHANISM Filed Aug. 26, 1953 2 Sheets-Sheet l 0ct. 26, 1954 E. A. ERlcsoN 2,692,929

TRIPPING MECHANISM Filed Aug. 26, 1953 2 Sheets-Sheet 2 Y fr? Ver? o/f --out in the appended claims.

Patented Oct. 26, 1954 TRIPPING MECHANISM .Eric A. Ericson, Blainville, Conn., assignor'to- General Electric-Company, :a New York corporation ,Application August 26, 1953, lSerial N 0. 376,676

4'7 Claims. l1

The hpresent 'invention relates fto improved tripping mechanisms and particularly to such mech- `ranisms or" 'improved sensitivi-ty.

Overload tripping mechanisms are Widely used "in Aair wcircuit breakers ci 'the vtype that may be lmanually opened and closed with a snap .action `:and tripped automatically in lresponse to an overfload `'current independently -o'f the position of the `manual-operafting member. There has been some 'diliiculty in `obtaining the `desired sensitivity lin kthe 'tripping mechanism, that is, `in obtainfi-ng fthe -desired amount of tripping movement lin --response vto `a given overload condition. It is :accordingly an important object of my invention "to providea Anew and improved `tripping mechanison having increased sensitivi-ty.

vIt is 'another object of my invention to provide yan improved tripping mechanism utilizing the additive deflections of vtwo overload responsive members toefiect the tripping operation.

Further objects and advantages of my invention will become apparent as the vfollowing description proceeds, reference being had to the accompanying dra-wing, and 'its lscope fpointed In Athe drawing, Fig. l is an elevational view, with the cover removed, of a manually operable, cur-rent 'responsively tripped circuit breaker embodying 'my 1in- 'vention and `shown in the .closed circuit position; Fig 2 is an elevational view of the saine breaker shown in the tripped position with the manual operating member held -in the closed position; Fig. f3 is a Vperspective View of 'a portion of the tripping 'mechanism `showing fthe vdetails of construction; Fig. 4 is an Ielevational view 'of va cir ycuitbrea'ker Vwith portion of `the cover broken away show-ing a `inodiiica'tion vof my invention `and with 'the parts `shown 'in the closed circuit position of the breaker; Fig. "5 is a similar view lof 'the saine breaker showing the .parts in the tripped position, the manual operating member :being retaineclin the closed position yand Fig. `6 'is -a vperspective viewvshowing therdetails of construction of 'the latch and tripping mechanism of the breaker :shown in Figs. f4 :and

Referring lnow :to the drawings, Vand particu -larly to Figs. .1,2 and `I haveshown my .invenft'lon embodied r`in van air .circuit breaker comprisn ing an .open-sided .housing .l formedof Asutabie rmolded plastic insulating :material and havin-g recesses `.therein for v:the reception and .retention .of an .operating mechanism. The housing ispro- 'vided with :a `meta-l top plate :2 havinvcr yreturn `bent :end Iportions 3 which :seat slots y(not shown.) in .the housing. Within the return bent end portions 3 are disposed A.threaded :nuts

(Cl. ZBO- 116) ladapteo'l to receive bolts (not shown) `for mounting circuit breaker `'upon a panel or the like. 'The operating 'mechanism `is adapted to be held in place in fthe housing 'l `by'a side cover plate k'(not shown?) which is adapted lto be connected to the housing by means of rivets passing through 'holes i5 'iin the housing l. The mounting 'nuts 4 fare disclosed and .claimed in my :co-pending applicatiomfSeriafl Norm-2,633, iled March i6, 1953, :and assigned 'to the 'sa-nie assignee as this applifcation.

Within the 4molded casing VI is `disposed a Amanual and automatic operating mechanism for shown vas an Leshaped 4Contact larm 9 pivotally mounted at a point intermediate `its ends upon ya iixed pivot pin tI E' carriedfby the `casing i. The contact arm El-l is mov-able 'ir-oni the closed circuit position, shown in iiig. `l, 'where the contacts Ei and il are 1in `engagernent to an open circuit position finot shown) where the contact member 'El engages o. fixed :stop `li formed on the casing. A second terminal member is seated in suitable positioning .recesses in the housino l fand projects irorn the bottom ci fthe housing vopposite the terminal rmember S.

'The L-shaped snow/able Aconta-ct arm 9 'is lmanually and rautonfiaticaliy movable between open and vclosed circuit positions byzineans of :an'automaticf ly reise-sable toggle `m'echenisin shown in fthe drawings lin closed and tripped positions. The actuating mechanism, 'shown at Fig. l in 'its closed position, Ar-:omprises a reicasable carrier :member is pivotally mounted lupfn a 'fixed pivot 'iis fredinzthecasi-ng i, and a pair of toggle links iT: zand is pivotally connected, respectively, 'to the .ripper 'of the carrier member 'i3 and the contact s .by means :oi movable pivot pins :and Hic, respectively. rSChe adjacent ends of thetoggle links are pivoted-together iat their lknee xby means oi a 'movable pivot :pin il. The toggle link :la :is connected 4n'termediete its ends to the pivot pin 1517 and .time lincludes a :portion it?) extending :beyond the and engaging .a ycompressionspring the other end of which is fixedly Areati-rd in suitable in the casing i.

The vrelsa-sable carrier rnc-riber i3 has mounted thereonxat its lower end va dablelatch member 13a, biased to an extendedposition with respect to the carrier i3 by spring `l-Sb disposed between the latch member lia and -a portion oi' ythe 'carrier :member i3., .The latch member i3d normally engages a current responsive tripping member I9 including generally parallel thermodeformable arms Illa and I9b. The member I9 is mounted in a suitable recess in the lower part of casing I and the arms lila and I9b thereof are connected in series circuit relation between the terminal i2 and the movable contact 'I by means of flexible conductors 2i! and 2l. A piece of sheet insulating material 22 is interposed between the arms to prevent a short circuit therebetween.

As is best seen from Fig. 3 the ends of the arms I9a and I9b engage the latch I3a in the closed circuit position of the breaker. The latch Ita is provided with an inwardly projecting stop I3c which rests upon an extension I9c of the arm I9a. A continuation of the latch I3d engages the end of the bimetallic arm i919 to prevent the movement of the carrier member I3 in a counterclockwise direction as long as the extension I3d is in engagement with the thermostatic arm. In order to prevent the latch member from short circuiting the bimetallic arms I9a and i917, a rivet 23 of insulating material is interposed between the extension I9c and the stop I3c on the latch.

Both of the arms I9a and |95 are arranged with the high expansion sides facing one another so that the deflection of both arms tends to separate the arms upon heating. Movement of the upper arm I9a lifts the latch member I3a against the bias of the spring I3b tending to release the extension I3d of the latch from the end of the other bimetallic arm leb. At the same time, the deflection of the arm I9?) is downward tending to release it from the extension I3d so that the tripping operation is eiected by the additive deflection of the two thermal elements. As indicated in the drawing, the end of the arm IQa is cut away or, in other words, the extension I9c is offset and the arm I3c of the latch is formed by bending up a portion of the latch so as to provide clearance for the counterclockwise movement of the latch as the breaker trips. As will be readily understood, the calibration of the device may be controlled by suitable adjustment of the calibrating screw 24 carried by a supporting plate 25 to which the xed ends of the bimetallic arms I9a and IElb are welded.

The manual operation of the circuit breaker is accomplished by means of the plunger 26 which is provided at its lower end with a link 21 connected to the knee pivot I'I. The plunger is suitably shaped to engage the upper end of a cylindrical flange 28 in the casing to provide a stop for the operating mechanism.

The operation of the illustrated embodiment of vmy invention is briefly as follows: With the parts in the closed circuit position as illustrated in Fig. 1 and with the operating plunger 26 held in a depressed or closed position, the parts are biased to move to the position shown in Fig. 2 by the spring I8 and are retained in the position shown in Fig. 1 by means of the latching member I3a. Upon an occurrence of an overload of sufficient magnitude, bimetallic arms I9a and ISb both tend to deflect outwardly, that is to separate. The upper arm I9a lifts the latch member I3a against the bias of the spring I3b and at the same time the arm Ib moves downwardly in a direction to release the extension i3d of the latch member. Both of these movements tend to release the mechanism which upon release moves under the action of the spring I8 to the position shown in Fig.2.

If the plunger 26 is now released, the spring I8 tends to lift the knee pivot I'I and return the operating plunger 26 to an upward or open position and at the same time to collapse the toggle upwardly and rotate the carrier member I3 in a clockwise direction until it is clear of the end of the thermal element at which time the breaker may be closed by pressing plunger 26 (provided the bimetallic arms have cooled sufficiently).

The particular mechanism for operating the breaker apart from the improved thermal trip described above is not a part of the present invention but is described and claimed in my copending joint application with Raymond N. Rowe, Serial No. 331,558, filed January 16, 1953, now Patent No. 2,673,267 dated March 23, 1954, and assigned to the assignee of this application.

In Figs. 4, 5 and 6 I have shown a modification of my invention in which a movable latch member is carried by a stationary part of the switch rather than by the movable carrier member I3 as described in connection with Figs. 1-3 inclusive. The breaker is in general of the same construction as that shown in Figs. 1 3 and the same reference numerals will be applied to corresponding parts. As illustrated in Figs. 4-6 the carrier member I3 is provided with an integral latching extension i3c for engaging, in the closed circuit position of the breaker shown in Fig. 4, the upper end of a latch member 23 which is mounted for both pivotal and vertical sliding movement in the slots 29 formed in the spaced side walls of the insulating casing. The thermal tripping member I9 includes a pair of spaced bimetallic arms 3U and SI in general similar to the arms Ilia and I9b but in this modiiication, there is no lateral oiset on either arm. The upper arm 32 engages a lateral extension 26a on the latch member 28 and the lower arm 3l engages the stop 28h formed by bending a portion of the latch member over so that it extends perpendicularly from one face of the latch. The latch is biased upwardly in the slots 29 by means of a compression spring 32. As before, it is necessary to insulate at least one of the arms from the latch and a rivet 33 of insulating material is interposed between the arm 3l and the stop 28h for that purpose.

As will be readily apparent to those skilled in the art, the arms 30 and 3| of the thermal mechanism both deflect in a direction to separate the arms upon an occurrence of an overload. Movement of the arm 3| in a downward direction tends to move the latch downwardly in the slots 29 against the bias of the spring 32 and at the same time the arm 30 deects upwardly tending to disengage it from the lateral extension 28a. Both of the movements, therefore, tend to cause release of the latching member which upon release tilts in a clockwise direction as illustrated in the drawing to release the latching tip I3c of the carrier member I3. It will be understood that in other respects the mechanism of the modification shown in Figs. 4-6 operates in the same manner as that described in connection with Figs. 1-3 inclusive.

It is inherent in the thermal tripping mechanisms described above that magnetic forces due to large overload currents also tend to cause tripping of the breaker. Since the bimetallic arms ISa and I9b or 30 and 3l lie in closely spaced relation and conduct current in opposite directions, the magnetic forces tend to separate them. In this manner, the thermal tripping action is accelerated by the magnetic action when the overload is great.

While in the specific embodiments of my invention illustrated the overload responsive elements are thermally actuated it is apparent that the broader aspects of the invention including the utilization of the additive deflections of a pair of overload responsive members may be carried out, for example, with magnetically actuated overload members.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention, and that it is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. An overload trip for a latch releasable mechanism including a biased member, a latch member for restraining said biased member and biased to one position, a pair of overload actuated members, one of said overload actuated members providing a stop for said latch member and movable upon the occurrence of an overload in a direction to release said latch and the other of said overload actuated members engaging said latch and movable in response to an overload to move said latch away from said one position whereby the movement of both said overload actuated members tends to release said biased member.

2. A thermal trip for a latch releasable mechanism including a biased member, a latch member for restraining said biased member and biased to one position, a pair of bimetallic members, one of said bimetallic members providing a stop for said latch member and movable upon an increase in temperature thereof in a direction to release said latch and the other of said bimetallic members engaging said latch and movable in response to a rise in temperature thereof to move said latch away from said one position whereby the movement of both said bimetallic elements upon a rise in temperature thereof tends to release said biased member.

3. A thermal trip for a latch releasable mechanism including a biased member, a latch member for restraining said biased member and biased to one position, a pair of longitudinally extending bimetallic members, one of said bimetallic members including means providing a stop for said latch member and movable upon an increase in temperature thereof in a direction to release said latch from said stop and the other of said bi-metallic members engaging said latch and movable in response to a rise in temperature thereof to move said latch away from said one position whereby the movement of both said bimetallic elements upon a rise in temperature thereof tends to release said biased member.

4. A thermal trip for a latch releasable mechanism including a biased member, a latch member slidably mounted on said biased member for restraining said biased member, a pair of longitudinally extending bimetallic members, one of said bimetallic members providing a stop for said latch member and movable upon an increase in temperature thereof in a direction to release said latch and the other of said bimetallic members engaging said latch and movable in response to a rise in temperature thereof to move said latch in a direction to release said latch from said rst bimetallic member whereby the movement of both said bimetallic elements upon a rise in temperature thereof tends to release said biased member.

5. A thermal trip for a latch releasable mechanism including a biased member comprising a latch member for restraining said member and biased to one position, a pair of longitudinally extending bimetallic members supported in parallel and closely spaced relation and electrically connected together at one end, means connecting said bimetallic elements in a circuit to be protected, one of said bimetallic elements providing a stop for restraining said latch member and movable upon an increase in temperature thereof to release said latch member, the other of said bimetallic elements engaging said latch member and movable upon an increase in temperature thereof in a direction to move said latch member from said one position against said bias and in a direction opposite to the direction of movement of said first mentioned bimetal element whereby the relative movement between said latch member and said rst mentioned bimetallic element is the sum of the movement of said bimetallic elements.

6. A thermal trip for a latch releasable mechanism including a biased member comprising a latch member for restraining said biased member and biased to one position, a pair of current responsive thermal elements, means connecting said thermal elements in a circuit to be protected by said mechanism, one of said thermal elements providing a stop for restraining said latch member and movable upon an increase in temperature thereof to release said latch member, the other of said thermal elements engaging said latch member and movable upon an increase in temperature thereof in a direction to move said latch member from said one position against said bias and in a direction opposite to the direction of movement of said rst mentioned thermal element whereby the relative movement between said latch member and said first mentioned thermal element is the sum of the movement of said thermal elements.

7. A thermal trip for a latch releasable mechanism including a biased member comprising a latch member for restraining said biased member, said latch member being supported for pivotal and reciprocating movement and biased to one position, a pair of longitudinally extending bimetallic members supported in parallel and closely spaced relation and electrically connected together at one end, means connecting said bimetallic elements in series in a circuit to be protected, one of said bimetallic elements providing a stop for restraining said latch member and movable upon an increase in temperature thereof to release said latch member, the other of said bimetallic elements engaging said latch member and movable upon an increase in temperature thereof in a direction to move said latch member from said one position against said bias and in a direction opposite to the direction of movement of said rst mentioned bimetallic element whereby the relative movement between said latch member and said rst mentioned bimetallic element is the sum of the movement of said bimetallic elements.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,010,414 Cubitt Dec. 5, 1911 2,677,548 Page Jan. 26, 1954 

